The present invention relates to a control system for use with a gas turbine and more particularly to methods and systems that adjust a model of the gas turbine in the control system when an operating parameter is unavailable or corrupt.
At least some known gas turbines include controllers that monitor and control their operation. The controllers govern the combustion system of the gas turbine and other operational aspects of the gas turbine, and typically execute scheduling algorithms that adjust control inputs to facilitate safe and efficient operation of the gas turbine.
Gas turbine controllers typically receive input values of measured operating parameters and desired operating settings that, in conjunction with scheduling algorithms, determine settings for control parameters to achieve the desired operation. Measured operating parameters may include compressor inlet pressure and temperature, compressor exit pressure and temperature, turbine exhaust temperature and generator power output. Desired operating settings may include generator power output and exhaust energy. Typical control parameters include fuel flow, combustor fuel splits, guide vane position, and inlet bleed heat flow. Scheduling algorithms can cause the gas turbine to operate at a desired state, such as at a desired power output level and/or within defined emission limits.
At least some known controllers include a Kalman filter to reconcile measured gas turbine performance data with predicted performance from a gas turbine cycle model. Known filter configurations for use with gas turbines require measured data parameters for at least the compressor exit pressure and temperature, turbine exhaust temperature, and net shaft output power. Data reconciliation can be difficult when one of the measured parameters is unavailable or corrupt. Net shaft power, for example, may be unavailable or difficult to measure in gas turbines in which the turbine shaft drives multiple components, i.e., where a steam turbine and a gas turbine are coupled to the same shaft. This configuration may make it difficult to quantify the power contribution of the gas turbine and the steam turbine. When a measure of gas turbine shaft power is unavailable as input to the filter, the filter may be under-constrained or the filter may reconcile the measured gas turbine performance data less effectively.